На вешалке в прихожей висит свитер, но у него слишком короткий рукав.

Because Russian chooses the preposition based on the spatial relationship:

• на вешалке = on the hanger / coat rack
• в прихожей = in the entryway / hall

So на is used for something being on a surface or support, while в is used for being inside a space.

Both phrases describe location, but they express different kinds of location.

They are both in the prepositional case singular.

That is because:

• на
  • prepositional is used for location: на вешалке
• в
  • prepositional is used for location: в прихожей

These are dictionary forms:

• вешалка → на вешалке
• прихожая → в прихожей

So the endings change because both nouns are used after prepositions meaning where something is.

Висит comes from висеть, which means to hang.

Russian often uses different verbs depending on an object's position:

• висеть = to hang
• стоять = to stand
• лежать = to lie

Since a sweater on a hanger is in a hanging position, висит is the natural verb.

English often just says is, but Russian usually prefers the more specific positional verb.

Russian word order is flexible, and this version sounds natural because it presents the scene first and then introduces the item.

The sentence structure is roughly:

• location: На вешалке в прихожей
• verb: висит
• subject: свитер

This often happens when Russian is introducing something that is present somewhere.

Compare:

• На вешалке в прихожей висит свитер = neutral, descriptive
• Свитер висит на вешалке в прихожей = also correct, but puts more focus on the sweater

So it is not about right versus wrong, but about information flow.

Свитер is in the nominative singular because it is the subject of висит.

You can think of свитер as the thing that is doing the hanging in the sentence grammatically, even though it is not acting voluntarily.

Russian very often uses the pattern у + genitive to express possession.

So:

• у него слишком короткий рукав = literally something like at it, the sleeve is too short
• natural English: its sleeve is too short or it has a sleeve that is too short

This pattern is extremely common in Russian.

If you said его рукав слишком короткий, that would also be grammatical, but it focuses more directly on the sleeve itself.
The version with у него is very natural when describing a feature or problem something has.

Yes, the form is the same as him/it after a preposition, but here it refers to the sweater.

Russian uses the same third-person pronouns for people and things:

• он = he / it for masculine nouns
• она = she / it for feminine nouns
• оно = it for neuter nouns

Since свитер is a masculine noun, the sentence uses него after у.

It cannot refer to прихожей or вешалке, because those are feminine, so the form would be у неё.

Because after many prepositions, Russian third-person pronouns take an extra н-:

• его → у него
• её → у неё
• их → у них

So this is a normal pronoun rule after a preposition like у.

Because the sentence is talking about one sleeve being too short.

So:

• слишком короткий рукав = one sleeve is too short

If both sleeves were too short, Russian would normally use the plural:

• у него слишком короткие рукава

English sometimes uses singular or plural a bit differently in these situations, so this can feel surprising at first.

Рукав is in the nominative singular, and короткий agrees with it.

In the structure у него слишком короткий рукав, the possessor is expressed separately by у него, while the thing possessed, рукав, stays in the nominative.

So:

• рукав = nominative singular masculine
• короткий = nominative singular masculine adjective agreeing with рукав

That is why it is короткий рукав, not some other ending.

In the present tense, Russian usually omits есть in this kind of sentence.

Compare:

• У него слишком короткий рукав = normal present-tense Russian
• literally: He/it has a sleeve that is too short

Russian often leaves out present-tense to be and also often leaves out есть in possessive statements when the meaning is already clear.

Using есть here would sound less natural unless you were stressing the existence of the sleeve or feature for some special reason.

Слишком means too, in the sense of more than is acceptable. It implies a problem.

• слишком короткий = too short

Очень just means very.

• очень короткий = very short

So in this sentence, слишком is important because the sleeve is not just short; it is unacceptably short.

Russian has no articles, so свитер can mean either a sweater or the sweater, depending on context.

The listener figures it out from the situation, previous conversation, or emphasis.

That is normal in Russian, and learners gradually get used to relying on context instead of articles like a and the.